This invention relates to an improved torque control, fluid shut-off, and reset mechanism for a fluid operated tool.
Fluid operated tools for driving fasteners and the like typically incorporate a rotary vane air motor to drive a rotary output shaft. Such tools are often equipped with a clutch mechanism responsive to the torque imparted by the tool onto the fastener. When a specific torque is reached, the clutch mechanism automatically slips and terminates further tool output to the fastener.
Starting the tool is often effected by positioning a bit or bit holder against the fastener and axially translating the bit holder by pushing it against the fastener. Such axial translation opens a fluid valve to the tool.
To combine start up control, torque control as well as a shut-off in a single mechanism is a desirable goal, and many tools include torque responsive shut-off mechanisms coupled with mechanisms for initiating operation of the tool. It is also desirable to have all of the operations of starting of the tool, torque control and shut-off as well as resetting associated merely with the activity of placing the tool against the fastener or removing the tool from the fastener.
There are many prior art references which disclose devices of this general nature. Of particular pertinence is U.S. Pat. No. 4,576,270 issued Mar. 18, 1986 for a torque control and fluid shutoff mechanism for a fluid operated tool. That patent and the references cited therein are incorporated herewith by reference.
U.S. Pat. No. 4,576,270 teaches the use of a bit which is axially translatable in order to open the inlet valve to the tool for operation of a rotary vane air motor. A clutch mechanism in the tool comprises opposed, interlocking jaws which are associated with a bit holder and shaft respectively. Upon reaching a threshold torque, the jaws separate by rotating relative to one another and cause the inlet valve to close and terminate fluid flow to the rotary vane air motor.
While the apparatus disclosed in the aforesaid patent is quite useful and successful, an improved mechanism having a simple construction and also having a reset capability associated with removal of the tool from the fastener has been sought. These are among the features and advantages sought which inspired the development of the present invention.